"Windows is indeed slower than other operating systems in many scenarios, and the gap is worsening." That's one way to start an insider explanation of why Windows' performance isn't up to snuff. Written by someone who actually contributes code to the Windows NT kernel, the comment on Hacker News, later deleted but reposted with permission on Marc Bevand's blog, paints a very dreary picture of the state of Windows development. The root issue? Think of how Linux is developed, and you'll know the answer.

These days lots of drivers are developed in the Linux kernel before the product ships. It takes a lot of time to get a product to ship. There are kernel drivers that were already done and releases before the product came to market. Yes, it also takes some time to get into distributions. This is true, but a lot of popular distributions now are on a 6 month release cycle. This helps a lot.

Obviously some companies are still not participating all that well. And I don't even mean Nvidia. They can't develop a driver for their desktop GPU in the open because they don't own the license on their own drivers. They hired an other company to develop it.

The mobile GPU-drivers from Nvidia are actually in the kernel and submitted by Nvidia.